Dust control methods are practiced in many industries performing solids handling. Dust control is required to protect the health and safety of workers, the integrity of the environment, and to mitigate the loss of valuable product.
For example, during the production of dry granular fertilizer there are mechanical conveyance steps that generate small particles of fertilizer that can be transported to undesirable locations by stray air currents. If the particle size is small enough the dust can remain suspended in the air for extended periods of time which can lead to the aforementioned safety, health and environmental problems.
Cake formation also presents problems in handling of bulk materials. In the case of fertilizer, the material is produced nearly continuously during the year, but the consumption is intermittent with the cycles of agriculture. As such, produced fertilizer is subject to storage in large piles within large barns. During these storage periods, a combination of factors (pressure, humidity, residual moisture, temperature cycles, etc.) can promote adhesion of the individual granules to form large, hard lumps, the undesired condition referred to as “caking”.
Coating the granular fertilizer with natural or petroleum oils or waxes is a historically established method for controlling dust and caking phenomena. Coating oil compositions for fertilizer comprising fatty acid methyl esters and bituminous materials such as asphalt, asphaltic tars, asphaltic pitches, coal tars, coal pitches, and the like are disclosed in U.S. Pat. Nos. 6,514,331 and 6,514,332. U.S. Pat. No. 6,776,832 discloses a coating oil composition comprising an oxidized oil in combination with a diluent where the diluents include methyl and ethyl esters of fatty acids, oils, and combinations thereof, glycerol and polyglycerol esters of fatty acids, oils and combinations thereof and light petroleum oil.